A method for reducing the fluctuation of the differential pressure of lubricating oil supply

Abstract

This application belongs to the field of lubricating oil supply design for aero-engines, and specifically relates to a method for reducing lubricating oil supply pressure differential fluctuations. It includes: Step 1, identifying the main causes affecting lubricating oil pressure differential fluctuations, including: excessively rapid vibration response of the pressure regulating valve; and excessively large orifice diameters of the pressure-sensing connector for the supply pressure and the bearing cavity pressure sensing connector of the pressure regulating valve; Step 2, determining methods to reduce lubricating oil supply pressure differential fluctuations based on the identified main causes, including: increasing the damping of the damping orifice of the pressure regulating valve slide valve; decreasing the orifice diameters of the pressure-sensing connector for the supply pressure and the bearing cavity pressure sensing connector of the pressure regulating valve; and installing throttle nozzles in the supply pressure and bearing cavity pressure sensing connectors respectively. This application can effectively reduce lubricating oil supply pressure differential fluctuations and improve the stability and reliability of the lubricating oil supply system.

Description

Technical Field

[0001] This application belongs to the field of lubricating oil supply design for aero-engines, and specifically relates to a method for reducing the fluctuation of lubricating oil supply pressure differential. Background Technology

[0002] Currently, the lubricating oil supply system of aircraft engines typically adopts a constant supply pressure differential, that is, a pressure regulating valve is installed in the lubricating oil supply line. The pressure regulating valve is an important component of the engine lubricating oil supply system, installed on the lubricating oil pump assembly. The purpose of setting up the pressure regulating valve is to ensure that the oil supply flow does not change with the pressure in the bearing cavity. In other words, the pressure regulating valve senses the changes in the pressure in the oil supply line and the pressure in the bearing cavity. The difference between the supply pressure and the bearing cavity pressure is the lubricating oil supply pressure differential. By adjusting the lubricating oil overflow, the difference between the rear bearing cavity pressure and the cavity pressure is kept constant.

[0003] Currently, the fluctuation of the lubricating oil supply pressure differential exceeds the limit, seriously affecting the oil supply capacity and operational stability of the aero-engine lubrication system. The main reasons are as follows: Aero-engines mostly use internally meshing gear pumps for lubricating oil supply. The flow rate of the gear pump is formed by the meshing of the gear teeth during rotation, changing the volume to draw in oil, and then continuously squeezing out the oil by changing the volume between the gear teeth. Gear pumps experience real pressure fluctuations during oil supply. Simultaneously, the pressure in the rear bearing cavity also fluctuates due to the influence of the oil-gas two-phase flow and the external cavity pressure. Furthermore, the length and direction of the pipeline, testing procedures, etc., also affect the fluctuation of the lubricating oil supply pressure differential, causing it to exceed the limit.

[0004] To address the issue of fluctuating lubricating oil supply pressure differential in aero-engines, a method for reducing lubricating oil supply pressure differential fluctuation has been summarized through analysis and experimental verification, which greatly increases the oil supply capacity and operational stability of the aero-engine lubricating oil system.

[0005] Therefore, it is desirable to have a technical solution to overcome or at least mitigate one of the aforementioned defects of the prior art. Summary of the Invention

[0006] The purpose of this application is to provide a method for reducing the fluctuation of lubricating oil supply pressure differential, so as to solve at least one problem existing in the prior art.

[0007] The technical solution of this application is:

[0008] A method for reducing fluctuations in lubricating oil supply pressure differential includes:

[0009] Step 1: Identify the main causes affecting lubricating oil differential pressure fluctuations. These main causes include:

[0010] The pressure regulating valve vibrates too quickly;

[0011] The pressure tap diameter of the oil supply pressure sensing connector and the bearing cavity pressure sensing connector of the pressure regulating valve is too large.

[0012] Step 2: Based on the main causes affecting lubricating oil pressure differential fluctuations, determine the methods to reduce lubricating oil supply pressure differential fluctuations, including:

[0013] By increasing the damping of the slide valve damping orifice of the pressure regulating valve;

[0014] The diameter of the pressure inlet of the oil supply pressure sensing connector and the bearing cavity pressure sensing connector of the pressure regulating valve is reduced, and throttle nozzles are installed in the oil supply pressure sensing connector and the bearing cavity pressure sensing connector respectively.

[0015] In at least one embodiment of this application, in step two, the diameter of the damping orifice of the pressure regulating valve is set to: diameter × length = Φ0.5mm × 12mm.

[0016] In at least one embodiment of this application, both the oil supply pressure sensing connector and the bearing cavity pressure sensing connector include a clamping screw and a rotary pipe connector. The clamping screw has an inner cavity and a pressure-guiding hole communicating with the inner cavity on its side wall. The rotary pipe connector is sleeved on the clamping screw through an annular connecting part.

[0017] In at least one embodiment of this application, a sealing ring is installed at the mating point between the annular connecting portion and the clamping screw.

[0018] In at least one embodiment of this application, in step two, the diameter of the pressure inlet of the sensing oil supply pressure connector and the sensing bearing cavity pressure connector is set to: diameter = Φ1mm.

[0019] In at least one embodiment of this application, four pressure-sensing holes are provided circumferentially on the sidewall of the clamping screw of both the oil supply pressure sensing connector and the bearing cavity pressure sensing connector.

[0020] In at least one embodiment of this application, in step two, the throttle nozzle is provided with an external thread, and the throttle nozzle is installed in the inner cavity of the clamping screw of the sensing oil supply pressure connector and the sensing bearing cavity pressure connector through a threaded connection.

[0021] In at least one embodiment of this application, the orifice diameter of the throttling nozzle is: diameter = Φ0.5mm.

[0022] The invention has at least the following beneficial technical effects:

[0023] The method for reducing the fluctuation of lubricating oil supply pressure difference in this application can effectively reduce the fluctuation of lubricating oil supply pressure difference and improve the stability and reliability of the lubricating oil supply system; it achieves the design that the lubricating oil pressure difference fluctuation does not exceed the limit value, which greatly meets the subsequent use requirements. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a slide valve according to one embodiment of this application;

[0025] Figure 2 This is a schematic diagram of the assembly of a sensing oil supply pressure connector or bearing cavity pressure connector according to one embodiment of this application.

[0026] in:

[0027] 1-Damping hole; 2-Pressure tapping hole; 3-Throttle nozzle; 4-Clamping screw; 5-Rotary pipe fitting. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are some, but not all, embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0029] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this application.

[0030] The following is in conjunction with the appendix Figures 1 to 2 This application will be described in further detail.

[0031] This application provides a method for reducing fluctuations in lubricating oil supply pressure differential, comprising the following steps:

[0032] Step 1: Identify the main factors affecting lubricating oil differential pressure fluctuations. The main factors affecting lubricating oil differential pressure fluctuations include:

[0033] The pressure regulating valve vibrates too quickly;

[0034] The pressure tap diameter of the oil supply pressure sensing connector and the bearing cavity pressure sensing connector of the pressure regulating valve is too large.

[0035] Step 2: Based on the main causes affecting lubricating oil pressure differential fluctuations, determine the methods to reduce lubricating oil supply pressure differential fluctuations, including:

[0036] By increasing the damping of the slide valve damping orifice of the pressure regulating valve;

[0037] Reduce the orifice diameter of the pressure tap of the oil supply pressure sensing connector and the bearing cavity pressure sensing connector of the pressure regulating valve, and install throttle nozzles in the oil supply pressure sensing connector and the bearing cavity pressure sensing connector respectively.

[0038] The method for reducing lubricating oil supply pressure differential fluctuation in this application first analyzes the lubricating oil supply system to identify possible causes of lubricating oil supply pressure differential fluctuation exceeding the limit, including: excessive vibration, oil accumulation in the bearing cavity pressure measuring pipe, excessively rapid vibration response of the pressure regulating valve, excessive elastic elements, and the pressure regulating valve spring being close to its natural frequency or resonant frequency. Through simulation and experimental analysis, the main causes affecting lubricating oil pressure differential fluctuation are found to be: excessively rapid vibration response of the pressure regulating valve, and excessively large orifice diameters of the pressure tap 2 of the pressure regulating valve's oil supply pressure sensing connector and bearing cavity pressure sensing connector.

[0039] The method for reducing lubricating oil supply pressure differential fluctuations in this application, based on the main causes analyzed above, can be achieved through the following two methods. One method is to increase the damping of the slide valve damping orifice 1 in the pressure regulating valve, thereby reducing the vibration response time of the pressure regulating valve. The damping of the slide valve damping orifice 1 in the pressure regulating valve (…) Figure 1 Increasing the damping of the valve can lengthen the response time of the internal cavity pressure of the spool valve to the oil supply pressure, reducing the responsiveness of the internal cavity pressure of the spool valve to the oil supply pressure on the oil supply line, decreasing the frequency of spool valve adjustment, and thus reducing the rate of change of lubricating oil overflow, thereby achieving the purpose of reducing the fluctuation of lubricating oil supply pressure. Another method is to reduce the diameter of the pressure tap 2 hole of the pressure sensing connector for the oil supply pressure and the pressure sensing connector for the bearing cavity pressure of the pressure regulating valve. The pressure sensing connector senses changes in oil supply pressure and bearing cavity pressure. When the diameter of the pressure tap 2 hole of the pressure sensing connector is too large (e.g., Figure 2 When the oil supply pressure and bearing cavity pressure fluctuate too much and too frequently, the spool valve adjustment becomes too sensitive to the oil supply pressure and bearing cavity pressure, the oil overflow rate changes too quickly, the oil supply pressure (differential pressure) fluctuates accordingly, and the oil supply pressure (differential pressure) fluctuates beyond the limit.

[0040] In the preferred embodiment of this application, improvements are made to existing pressure regulating valves from two aspects:

[0041] (1) Increase the damping of the slide valve to reduce the responsiveness of the internal cavity pressure of the slide valve to the oil supply pressure on the oil supply line.

[0042] Specific measures: Set the diameter of the damping hole 1 of the slide valve in the pressure regulating valve to: diameter × length = Φ0.5mm × 12mm.

[0043] The pressure regulating valve senses changes in the oil supply pressure and the bearing cavity pressure. When fluctuations in the oil supply pressure and bearing cavity pressure are transmitted to the damping orifice 1 inside the spool valve of the pressure regulating valve through the oil control circuit, if the damping of the spool valve is too small, the spool valve will react too quickly to changes in the oil supply pressure and bearing cavity pressure. This will also cause the spool valve's regulating frequency to change too quickly, leading to changes in overflow, and fluctuations in the oil supply pressure and oil supply pressure differential. Therefore, increasing the damping of the spool valve can reduce the responsiveness of the internal cavity pressure of the spool valve to the oil supply pressure on the oil supply line, thereby reducing fluctuations in the lubricating oil supply pressure.

[0044] (2) Reduce the diameter of the pressure inlet 2 of the pressure regulating valve sensing oil supply pressure connector and the bearing cavity pressure connector, and add a throttle nozzle 3 to the sensing oil supply pressure connector and the sensing bearing cavity pressure connector to reduce the problem of excessive and rapid fluctuation of oil supply pressure and bearing cavity pressure.

[0045] Specific measures: Set the diameter of the pressure tap 2 of the oil supply pressure sensing connector and the bearing cavity pressure sensing connector in the pressure regulating valve to be Φ1mm, and add a throttle nozzle 3 with a diameter of Φ0.5mm to each.

[0046] In this embodiment, as Figure 2 As shown, the oil supply pressure sensing connector and the bearing cavity pressure sensing connector have the same structure, both including a clamping screw 4 and a rotary pipe connector 5. The clamping screw 4 has an inner cavity, and a pressure-guiding hole 2 communicating with the inner cavity is formed on its side wall. One end of the inner cavity has an opening, and the opening of the clamping screw 4 is provided with internal and external threads. The throttle nozzle 3 is provided with external threads. The throttle nozzle 3 is installed in the inner cavity of the clamping screw 4 of the oil supply pressure sensing connector and the bearing cavity pressure sensing connector through a threaded connection. The rotary pipe connector 5 is sleeved on the clamping screw 4 through an annular connecting part and is sealed with a sealing ring. Finally, the clamping screw 4 is threadedly connected to the pressure regulating valve housing. In this embodiment, four pressure-guiding holes 2 are formed circumferentially on the side wall of the clamping screw 4 of both the oil supply pressure sensing connector and the bearing cavity pressure sensing connector.

[0047] Because the oil supply pump is a positive displacement pump, the oil supply pressure will fluctuate to some extent even when the rotational speed and inlet / outlet conditions remain constant. Generally, this fluctuation should be normal and be a high-frequency fluctuation related to the rotational speed and number of teeth. Additionally, the oil supply pressure will also fluctuate due to factors such as pipeline elasticity and vibration environment. The bearing cavity pressure will also fluctuate to some extent due to the presence of an oil-gas mixture and pipeline vibration. When testing this pressure, damping measures such as throttling orifices, spiral tubes, shelves, and buffer bottles can be used to shield these fluctuations and obtain the true pressure value meaningful for design. When the fluctuations in oil supply pressure and bearing cavity pressure are too large and too frequent, the spool valve adjustment will become overly sensitive to the oil supply pressure and bearing cavity pressure, the lubricating oil overflow rate will change too quickly, and the lubricating oil supply pressure (differential pressure) will fluctuate accordingly, ultimately leading to excessive fluctuations in the oil supply pressure (differential pressure). Therefore, in order to reduce the fluctuation of lubricating oil pressure and lubricating oil pressure difference, it is necessary to first reduce the control pressure fluctuation of the differential pressure regulating valve, that is, to add a throttle nozzle 3 at the oil supply pressure and bearing cavity pressure to increase damping and reduce its impact on the fluctuation of the slide valve.

[0048] After adopting the above solution, the risk of pressure regulating valve fluctuations exceeding the limit value is eliminated, the stability and reliability of the lubricating oil supply system are greatly improved, and it has good practicality.

[0049] The method for reducing the fluctuation of lubricating oil supply pressure difference in this application can effectively reduce the fluctuation of lubricating oil supply pressure difference and improve the stability and reliability of the lubricating oil supply system; it achieves the design that the lubricating oil pressure difference fluctuation does not exceed the limit value, which greatly meets the subsequent use requirements.

[0050] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for reducing fluctuations in lubricating oil supply pressure differential, characterized in that, include: Step 1: Identify the main causes affecting lubricating oil differential pressure fluctuations. These main causes include: The pressure regulating valve vibrates too quickly; The pressure tap diameter of the oil supply pressure sensing connector and the bearing cavity pressure sensing connector of the pressure regulating valve is too large. Step 2: Based on the main causes affecting lubricating oil pressure differential fluctuations, determine the methods to reduce lubricating oil supply pressure differential fluctuations, including: By increasing the damping of the slide valve damping orifice of the pressure regulating valve; Reduce the orifice diameter of the pressure inlet of the oil supply pressure sensing connector and the bearing cavity pressure sensing connector of the pressure regulating valve, and install throttle nozzles in the oil supply pressure sensing connector and the bearing cavity pressure sensing connector respectively. Both the oil supply pressure sensing connector and the bearing cavity pressure sensing connector include a clamping screw and a rotating pipe connector. The clamping screw has an inner cavity and a pressure-guiding hole communicating with the inner cavity on its side wall. The rotating pipe connector is sleeved on the clamping screw through an annular connecting part.

2. The method for reducing the fluctuation of lubricating oil supply pressure differential according to claim 1, characterized in that, In step two, the diameter of the damping orifice of the pressure regulating valve is set to: diameter × length = Φ0.5mm × 12mm.

3. The method for reducing the fluctuation of lubricating oil supply pressure differential according to claim 1, characterized in that, A sealing ring is installed at the point where the annular connecting part mates with the clamping screw.

4. The method for reducing the fluctuation of lubricating oil supply pressure differential according to claim 3, characterized in that, In step two, the diameter of the pressure inlet of the oil supply pressure sensing connector and the bearing cavity pressure sensing connector is set to: diameter = Φ1mm.

5. The method for reducing the fluctuation of lubricating oil supply pressure differential according to claim 4, characterized in that, The pressure-sensing connector for oil supply pressure and the pressure-sensing connector for bearing cavity pressure both have four pressure-sensing holes circumferentially opened on the side wall of the clamping screw.

6. The method for reducing the fluctuation of lubricating oil supply pressure differential according to claim 5, characterized in that, In step two, the throttle nozzle is provided with external threads, and the throttle nozzle is installed in the inner cavity of the clamping screw of the sensing oil supply pressure connector and the sensing bearing cavity pressure connector through threaded connection.

7. The method for reducing the fluctuation of lubricating oil supply pressure differential according to claim 6, characterized in that, The throttling nozzle has a throttling orifice diameter of Φ0.5mm.

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